Valve gear fob reversible recipro



Sept. l2, 1939.v H. J. LENTz VALVE GEAR FOR REVERSIBLE RECIPROCATING FLUID PRES ENGINES, ESPECIALLY FOR LOCOMOTIVES SURE 5 Sheets-Sheet 1v Filed Feb. 25, 1938 Sept. 12, 1939. H, 1, LENTZ 2,172,562

VALVE GEAR FOR REVERSIBLE RECIPROCATING FLUID PRESSURE ENGINES, ESPECIALLY FOR LocoMo'rIvEs Filed Feb. 25, 1958 5 Sheets-Sheet 2 sept. 12, 1939. H. J. LENTZ 2,172,562

VALVE GEAR FOR REVERSIBLEVRECIPROGATING FLUID PRES ENGINES. ESPECIALLY FOH LOCOMOTIVES SURE Filed Feb. 25, 19:58 5 sheets-sheet 5 Sept. l2, 1939. H J LENTz l 2,172,562

vALvE GEAR EoR BEvEnsILE' REcIPRocATING FLUID PRESSURE ENGINES, EsPEcIALLY Foa LocoMoTIvEs Filed Feb. 25, 1958 5 Sheets-Sheet 4 Sept. l2, 1939) VH J..| `l-:NT2 I` 2,172,562

VALVE GEARLFOR REVERSILE RECIPROCATINGFLUID PRESSURE ENGINES, ESPECIALLY FOR LOCOMOTIVES \Fi1ed Feb. 251938 5 sheets-sheet 5 Patented Sept. 12, 1239 UNITED. STATES `vALvE GEAR Fon ymtvERsILE RECIPRo- OATING FLUm PRESSURE ENGINES,

ESPECIALLY FOR LOCOMOTIVES Hugo Johannes Lentz, Vienna, Austria.

Application February z5, 193s, serial No. 192,614 n1 Great. Britain septemberzo, l193':

8 Claims.

The invention relates to a special construction of a valve gear for'reversible fluid pressure en-` gines especially for locomotives wherein the valves are actuated by rotary control cams and the adjustment of the control cams is effected by control grooves in the cam shaft said grooves extending partly in axial direction and are partly helical, coupling elements connected with the control cams engaging in said grooves to bring the 10 control cams into the actually required position by which the' cam shaft is axially shifted, as described in my patent application Serial No. 192,121

of February 23, 1938.

It is desirable andi/ery advantageous to be able to set the initialposition of the control cams independently of the law prescribed by the shape of the control grooves and to thus displace the position of the points of control so that the most favorable steam distribution is obtained for the type of engine in question. For this purpose the control cams are adjustable in their angular position relatively to the coupling element. engaging in the control groove of the cam shaft by means of a manually adjustable clutch.

The clutch, which may be of any suitableeonstruction, establishes a rigid connection between the cam and the part which carries the coupling element engaging and guided in the control groove.A

To enable the control points, determining the exhaust lead and the compression, to be adjusted within wide limits, two different cams are further provided according to the invention for of each cam is only operative for one direction of rotation, whereas the other side is covered by the y other ca m and consequently inoperative. When the direction/of rotation is changed the sides of the cams which were previously operative are coveredand therefore inoperative, ','v'hereas those sides which were formerly covered now effect 0 the opening and closing of the valve. Thus it is possible to render adjustable for each direction of rotation the correspcnding controlling side independently of its other side. this being effected therebythat eachnoi.' these two cams consists ofl '55 two halves which are relativelyadjustable and tion of the control grooves. Therefore, there is alallow of a relative displacement of the controlling faces of each cam. The displacement of the cams or of the bearing bodies carrying them is eifectedby coupling elements mounted on these bodies and engaging into the catch grooves in the cam 5 shaft. As each control groove is composed partly of axially directed and partly of helically curved portions these coupling elements were up to the present constructed as rollers. However, this is open to the disadvantage that there is only line- 10 contact-between roller and controlgroove.

This invention represents a further important improvement of the cam drive' in that'the coupling elements, are constructed as rhomb-shaped prisms, mounted on the bearing bodies, of which 15 two opposite -side faces are fiat and adaptlthemselves to the sides of the straight cam grooves, whereas the two other opposite faces are helically,` curved and fit in the helically curved porways a surface-contact between the coupling ele- .20 ments and the cam shaft in all positions this surface contact enabling a frictionless and relialble transmission of power from the cam shaft to the camsv and also ensures perfect guiding.

The invention'also relates to means for enabling an axial ldisplacex'nent of the cam shaft.

An embodiment of the invention is illustrated in the accompanying drawings, in which:

Fig. 1 is' a crosssection on line I-I of Fig. 2 through the upper portion of the steam cylinder in the direction of the cam shaft mounted transversely therein. y Fig. 2 isa longitudinal section through the upper part of the cylinder, the left half being a section on line II-II of Fig. 1 viewed in the direction of the admission valve spindle and the right half a section on line V--V of Fig. 1 in the direction of the exhaust valve spindle. y

Fig. 3 shows in end view one of the admission 40 cams (admission lead cams) with its bearing body viewed in the direction of the arrow at section line III-III of Fig. 1. l

Fig. 4 is a longitudinal section through the admission cam and its bearing body taken on line IV-IV of Fig. 3.

` Fig. 5 shows the other admission cam (cut-olf cam) viewed in the direction of the arrow on line.l II-II of Fig. 1.

Fig. 6 is an end view of the'exhaust lead cam 50 whereas I Fig. 'I is a side elevational view of the same cam.`

Fig. 8 shows the corresponding bearing body in end view. l

Fig.9 is a similar view of the exhaust lead cam to that shown in Fig. 6 only with the difference that the liftingfaces are moved further apart.

Fig. 10 shows thecompression cam in end view. Fig. 11 is a side elevation of Fig. l0. Fig. 12 shows the relative positions of the exhaust lead and compression cams during running forwards and Fig. 13 their position during running backwards. Y

Fig. 14 shows in elevation a portion of the cam shaft with control groove and a .prismatic coupling element engaging therein.

Fig. 15 is a longitudinal section through a bearing body for the cams with rhomb-shaped guide prisms distributed on theirV inner circumference.

Fig. 16 is an end view of Fig. 15.

Fig. 1'7 shows in part developed state the cam shaft with the control grooves milled therein.

I designates the cylinder of the steam engine with gear boxes mounted on its ends and accommodating the steam passages for the steam admission and exhaust and the control valves. In the middle of the gear box and transversely thereto is 'the cam shaft I5 with the admission and exhaust camsfarranged thereon.. On each side ofthe cam shaft an admission valve 3 and an exhaust valve 4 are arranged in the gear boxes, their spindles I3 and I4 being parallel the one to the other and directed towards the cam shaft. One pair of valves controls the steam admission and exhaust on the front end of the cylinder and the other pair of valves the 'steam admission and exhaust at the rear end of the cylinder. Y'

The live steam is fed through a ange 5 at each end of the. cylinder .to the admission valve there situated. When the admission valve 3 is open the steam passes into the cylinder in front of the piston through one of the passages 6 formed one in each end of the cylinder. When the exhaust valve at the other end of the cylinder is open the expanded steam on the corresponding side of the piston escapes throughthe passage 6 at this end of the cylinder into an exhaust steam chamber 1 to which the exhaust pipes are connected.

The control valves 3 and 4 are double seated valves. Their spindles I3 or I4 are journalled in insert bushes I pressed into bores in the gear box 2. The spindles have labyrinth grooves which form a packing for the 'spindles towards the cam chamber 8 situated between the gear boxes 2. A cam shaft FI5. extends through the cam chest 8 which is closed by `a cover 8 to render easily accessible the gear parts situated in the cam chest.

The cam chest accommodates cams E1 and E2 for actuating the admission valves 3 and cams A1 and An for actuating the exhaust valves 4. These cams are, however, not mounted directly on the shaft l but with the aid of oconical seating on separate bearing bodies K1, K2 and L1, L1 respectively loosely slipped on the shaft I5. These bearing bodies carry coupling elements I8, which en# gage in control grooves I8 formed in the shaft I5. Toprevent the bearing bodies from shifting in the chamber 8 the inner bearing bodies are held apart by a spacing ring I I on shaft I5, whereas the outer bearings bear against bushes.

The admission valves are actuated by intermediate levers 22, oscillatable about an axle 23 in cam chest'8." A rocker 2li is oscillatable about a pin 2l on each of these intermediate levers and the curved arms W1 and W1 of the rocker contact like a rolling lever with the circumference of the cams E1 and Ez.

The two admission cams E1 and Ez (Figs. 3 to 5) rest on a cone 32 of their respective bearing be displaced through a certain angle bodies K1 or K2. They carry each on their inner surface two diametrically opposite bolts 33 with screw threaded ends 34 and nuts 35. The bolts 33 are guided in slots 36 extending concentric tothe axis and their centre lines are displaced relatively to those of the couplingelements I8 through an angle a. The slot is of such a length that the bolts and consequently the cams E1, E2 can be shifted a short distance on their bearing bodies K1, K2 out of their central position in both directions, for example at the most through an angle ,3/2, independently of the displacement caused by the control groove. It is thus possible to adjust by hand the moment at which the advance infiow takes place within the necessary limits.- the cam being secured in its adjusted position by tightening nut 35.

During forward running of the engine the admission cam E1 controls the admission lead' whereas the cam Ez controls the cut-off. In order to indicate the relative positions of the two cams, the position of the admission lead cam E1 is shown in dot-dash vlines in Fig. 5. When the direction of rotation is reversed the function of the cams changes accordingly, so that the cam E2 now controls the admission lead an the cam E1 the cut-off.

Two cams A1 and A2 are provided for actuating the exhaust valves 4, the cam A1 contnolling only the exhaust lead and the 'cam Aa only the compression. In order to increase by hand the width of these cams, measured in angles, and to thus change the commencement'of the exhaust lead or the commencement of the compression, independently of the adjustment determined by the control groove I9, each of these cams is composed of two claw-shaped interengaging cam halves A1 and A1'and A2 and A2 which are relatively adjustable and fixed with conical seat on the cone 32 of their bearing bodies L1 and L2 respectively. Each 'of these cani halves has a nose 58 or 50', which ts in a corresponding recess 5I', 5I of the other cam half. The recesses 5I, 5I are so dimensioned that each of the two cam halves can- The nose-shaped parts of both cam halves carry the operative faces .of the cams. The operative faces consequently extend over the entire length of the cams, so that the intermediate lever 28 coop- The intermediate levers- 28v are oscillatably mounted on axles 29 in the cam chest 8, their free ends acting on the spindles of the exhaust valves.

`The two cam halves are secured on the cones 32 of their corresponding bearing bodies L1, L2 in a similar manner to the admission valves. For this purpose bolts 33 with screw threaded portions 34 and nuts 35 are mounted on the outer cam the two cam halves can, however, be relatively' displaced so that the operative faces cover a larger angle range, as shown in Fig. 9.

The compression cam illustrated in Figs. and 11 is subdivided into two cam halves Az and Az' in a similar manner tothe exhaust lead cams,

these halves being similarly constructed and fixed erating with the cam rests on its full width on the"y cam.

on their corresponding bearing bodies In by simof cam A1 determines the exhaust lead and the running .off surface b of the cam A2 the commencement of the compression. At the same time the running off face b of cam A2 and the lifting face a of cam A1 are actually covered by the other cam and consequently are inoperative.

If the direction of rotation is in the opposite direction (Fig. 13) the cams are displaced by the control groove I9 so that the lifting face a. of cam A1 determines the opening of the exhaust valve and the running off face b of cam Az `the closing of the exhaust valve.

Apart from this adjustment determined by the shape of the control grooove the-faces a,.a and b,. b' can vbe adjusted by hand in the manner above described and thereby the time for the commencement of the exhaust lead and of the compression for both directions of rotation can be adapted to the actual working requirements.

The individual cams receive the rotary motion from the cam shaft I5 as the coupling elements I8 engaging in the control groove I9 drive the bearing vbodies of the individual cams. In the cams illustrated in Figs. 1 to 11 the coupling elements' consist of .cylindrical pins I8, the Shanks I8 of which engage .in bores in' the bearing bodies. Coupling elements of such shape only have line contact with the control grooves i. e. produce high pressures and cause heavy wear.

In order to effectively overcome this objection rhomb-shaped prisms 54 (Figs. 14 to 16) are arranged on the bearing bodies. lTwo Opposite side faces 55, 55 of `the prisms are flat and` adapt themselves to the flat side faces of the straight control groove ISa. The two other opposite side faces 56, 56' of the prisms are helically curved and adapt themselves to the helical shape of the control groove I9. Such a construction of the coupling elements allows displacement both in the straight and also in the helical control groove. In all positions it produces a` surface-contact. At the same time several control grooves maybe formed inthe periphery of the'cam shaft, in which engage the suitably distributed coupling elements 54 of the indivflual bearing bodies. Thus a light running adjusting arrangement almost free from wear is produced for the control cams.

The adjustment of the control cams, so that they give the desired cutoffs during running forwards and backwards is effected by axial dis.

placement of the cam shaft I5. Consequently this shaft I5- is shiftably mounted in the cam chest il and the control grooves I9 in this shaft effect the adjustment of the different cams. The drive of the cam shaft I5 and the arrangement for its adjustment are, las shown in Fig. 1, preferably accommodated in a casing mounted on the side of the cam chest 8 and composed of two parts I6 and I1. A sleeve 25 is mounted in this casing through the intermediary of bearing bushes 24. A worm wheel 26 fixed on this sleeve 25 meshes with a second worm wheel 21 keyed on a short axle 30 journalledlin the casing part Il and driven by a rotating part of the locomotive.

For transmitting the rotary movement of the worm wheel 2E to the cam shaft I5 the shaft I5 has a collar 38 which has in its periphery four recesses 31 in which tooth-like projections 39 on the inner surface of sleeve 25 engage. projections extend parallel to the cam shaft and maintain a coupling of this shaft with the driving wheel even when the cam shaft I5 is shifted towards the left for vchanging thel cut-off and the direction of rotation.

The axial displacement of the cam shaft I5 is effected by a setting device arranged directly adjacent the collar 38. This device comprises a setting sleeve 43 in which a journal 4I forming an extension of camshaft I5 is rotatably mounted in roller bearings 42 and which is secured against rotation by a longitudinal slot 44 with a prism 46 slidably engaging therein.

The setting sleeve 43` is attened on the side opposite the longitudinal groove and has teeth 4l projecting obliquely to the axial direction. These teeth mesh with the teeth 49 of a rack 48 arranged parallel tothe cylinder and shiftably mounted in a bore in casing part I'I. A rod system not shown in the drawings is connected to this rack 48 and extends to the locomotive cab. When the rack 48 is pulled the sleeve 43 is shifted in its guide 40 towards the left and shifts the cam shaft so that the control groove I9 in the latter effects the adjustment of the cams E1, E2 and A1, A2 in the manner above described.

I claimr- 1. Valve gear for reversible fluid pressure engines especially for locomotives, comprising in combination a rotary cam shaft having in its periphery control grooves extending partly in axial direction and partly along a helical path, bearing bodies loosely mounted on said shaft, two admission valve control cams, and -two exhaust valve control cams, each of said cams adjustablyv mounted on the cam shaft Aby means of a manually adjustable clutch, coupling elements on each of said clutchbodies engaging in the control grooves in said shaft, and means for axially shifting said shaft.

2. Valve gear as specified in claim 1, in which the bearing bodies have each a conical seat for carrying one of the control cams and slot guides, screw bolts on the control cams guided in said slots, and nuts on said bolts forclamping the cams in the actual position adjusted by hand, the length of said slot guides limiting the range of adjustment of the control cams.

3. Valve gear as specified in claim l, in which each of the two exhaust cams comprises two interengaging and relatively adjustable clawshaped halves for hand adjustment of the control points for the exhaust lead and for the commencement of the compression.

4. Valve gear as specified in claim 1, in which each of the two exhaust cams comprises two interengaging and relatively adjustable clawshaped halves for hand adjustment of the control points f or the exhaust lead and for the commencement of the compression, the operative faces on each cam half of the two exhaust cams being situated on the portion which engages over the other cam half.

5.. Valve gear as specified in claim 1, in which each of the coupling elements between the cam shaft and the cams consists of a prism on the corresponding bearing body, two opposite side faces of the prism being flat and conforming with the sides of the axial control grooves, whereas the I two other opposite sides of the prisms are curved in helical shape vto fit the helical portions of the control grooves.

These 6. In a, valve gear as specified in claim 1, a u

driving wheel coupled with one end of the cam shaft, an element for shifting said cam shaft arranged co-axally with said driving wheel, a cam chest accommodating said cams, and a casing extending directly from said cam chest accomsleeve engaging in said recesses and maintainin the driving connection between said wheel an said cam shaft irrespectively of the axial displacement of said cam shaft.

8. In a .valve gear as specied in claim 1, a journal formed on the end of the cam shaft, a

setting sleeve secured against rotation on said journal, oblique teeth on said sleeve, and a. rack arranged perpendicularly to said sleeve and meshing with said teeth.

HUGO JOHANNES LENTZ. 

